Understanding this iRule - to resolve upto 15 seconds lag while playing videos

Hi,

I need help in understanding the iRule below. I am also mentioning the VS setting for clarity.

    virtual vs_cdms_http {
    snat automap
    pool pool_cdms_http
    destination 10.0.2.10:http
    ip protocol tcp
    rules ir_cdms_http
    persist pr_dms_source_addr
    profiles {
    http {}
    tcp {}
    }
}

rule ir_cdms_http {
   when HTTP_REQUEST {
     SET DEBUG TO 1 TO TURN ON AND 0 TO TURN OFF
    set DEBUG 0
    set defaultURI "/windows/test.txt"

    if { $DEBUG } {  log local0. "DMS URI: [HTTP::uri]" }
    switch -glob [HTTP::uri] {
      "/" { set uri $defaultURI }
      default { set uri [string tolower [HTTP::uri] ] }
    } 
    }

   when HTTP_RESPONSE {
    set pserver [persist lookup source_addr [IP::client_addr] node] 

  if { $DEBUG } {  log local0. "DEBUG LINE TURN OFF IN PROD URI $uri PServer $pserver:Client Ip [IP::client_addr]:Active Members [active_members [LB::server pool]]" }
  switch -glob $pserver {
   10.0.0.1 { HTTP::redirect "http://abc001$uri"}  
   10.0.0.2 { HTTP::redirect "http://abc002$uri"}
   default {  HTTP::redirect "http://$pserver$uri" } 
  }
}
}

May I know, how this iRule will be effecting/processing the traffic?

Your help will be kindly appreciated.